1. Field of the Invention
The present invention generally relates to a gaseous blend of CO2 and OX and a method for applying the gaseous blend that can be utilized to significantly reduce the biological load on consumer products such as food products, botanicals and cosmetic ingredients, which have traditionally been treated with commercial sterilants or fumigants such as ethylene oxide, propylene oxide, methyl bromide, hydrogen phosphide, phosphine, steam (heat), irradiation, and the like. The gaseous blend of CO2 and Ox and method for applying the gaseous blend can also be used to reduce biological load in enclosed structures and on transportation containers (e.g., wooden pallets and crates), which are often used to store food products, as well as to reduce biological load on other commodities, and, in particular, on soil.
2. Background of the Technology
Damage to food products, building structures and other commodities by insects and other pests accounts for billions of dollars of losses in the United States annually. Traditionally, a number of fumigants have been utilized to control these pests by their application under air tight tarpaulins, in sealed rooms and in steel chambers. The most widely used fumigants are methyl bromide, hydrogen phosphide and hydrogen cyanide. As disclosed in U.S. Pat. Nos. 6,284,193 and 6,334,979, many of these compounds pose hazardous conditions for application personnel and can form deleterious residues on the foodstuffs, building structures, transportation containers and commodities that are treated. Furthermore, some of the traditional fumigants have been identified with the formation of carcinogens and mutagens, thereby limiting the products that can be treated. All three of the primary employed gaseous fumigants; i.e., methyl bromide, hydrogen phosphide and hydrogen cyanide, have faced major regulatory restrictions and/or total phase out agreements. With these limitations in mind, the search for effective alternatives has led to the use of materials such as methyl iodide and sulfonyl fluoride. Unfortunately, these alternatives have limitations because of factors such as worker exposure, halogen content and damage to certain commodities.
Ozone (O3) and its primary active component, atomic oxygen, have been used in water and commodity sterilization for about 100 years. Carbon dioxide (CO2) has been used in conjunction with various pesticides to enhance their effectiveness by increasing the target organism's rate of respiration. As discussed in more detail below, however, prior treatment methods using O3 or CO2 have proven ineffective for many applications.
U.S. Pat. Nos. 5,624,635 and 5,566,627 disclose a method and apparatus for use of O3 to treat soil.
U.S. Pat. Nos. 4,889,708; 5,403,597; 5,897,841 and 6,027,667 disclose the use of CO2 as a carrier gas for phosphine fumigant.
U.S. Pat. No. 4,200,656 discloses the use of CO2 as a carrier for methyl bromide in fumigation.
U.S. Pat. No. 4,998,377 discloses the use of CO2 as a carrier for methyl bromide and hydrogen phosphide in fumigation.
U.S. Pat. No. 5,678,352 discloses the use of CO2 as a carrier for toxic agents such as methyl bromide during fumigation.
U.S. Pat. No. 5,464,457 discloses the use of an ammonium carbonate ingredient that decomposes to ammonia and CO2 in order to fumigate a plot of soil.
U.S. Pat. No. 4,989,363 discloses application of CO2 in pesticidal quantities for fumigation. The process disclosed in U.S. Pat. No. 4,989,363 requires administration of CO2 for a period of time of at least about 5 days.
U.S. Pat. No. 5,011,699 discloses the use of O3 and CO2 in specified ratios, i.e., from 1:2 to 2:1, to sterilize foodstuffs at reduced temperatures.
U.S. Pat. No. 6,066,348 discloses the use of O3 and CO2 at reduced temperature to disinfect a foodstuff.
Japanese Patent Publication No. 02076562A (Abstract) discloses the use of O3, CO2 and N gas to sterilize foodstuffs.
U.S. Pat. Nos. 6,283,193 and 6,334,979 disclose methods that use a gaseous mixture of oxygen-containing gases, i.e., O3, O2 and O1, hereinafter referred to as Ox, in a vacuum chamber to reduce biological loads on foodstuffs and other commodities. Although such use of Ox has proven successful in controlling insects and microbiological concerns for selected fruits, vegetables and other botanicals, because of phyto-toxic issues and the fact that O3 readily converts to oxygen when exposed to an oxygen-rich atmosphere, there remains a need to treat foodstuffs and other commodities that cannot withstand treatment under vacuum.
The present inventors have surprisingly discovered that regardless of whether a vacuum is employed, for a number of commodities, a gaseous blend of CO2 and Ox having a specified ratio, i.e., about 90-99% CO2 and about 1-10% Ox, preferably about 98-99% CO2 and about 1-2% Ox, is highly effective in biological burden reduction. This surprising discovery permits the application of gaseous Ox to products in many environments.